Jonti's Web Site

A place where I put things on the Web


This is a reasonably live feed from under the sea in a marine reserve in Wellington. It only works during the day for obvious reasons. It uses a single stainless steel rope from the shore to provide power and a bidirectional communication channel. Currently not working due to hardware failure but hopefully it will be running again in the future.

RIP sweet pudwing


Pudding my love

Pudding, I will always love you and you will be in my heart wherever I go and what ever I do. I've loved you being here with me, bringing me comfort, joy and happiness. You made the world seem safe and comforting even when bad things where happening in the scary outside world. I will cherish the time we spent together.

I Love you so much and my heart breaks in pain to be here without you. I wish I could have cured you of the cancer that took you away from me too soon and that caused suffering to both you and me. I'm so sorry I failed to save you; I tried. You will always be a part of who I am and I will love you forever. Be a good girl, da da loves you, and lots of kisswings; Kiss kiss kiss.


JSquelch: Records audio when it hears voice

An application that records audio to disk when it hears voice or other noncontinuous signals. It ignores constant interference such as sine waves. It also ignores any random noise such as any color of Gaussian noise. The idea of this program was for recording HF plane to tower contacts and not to record the majority of time where you just hear hiss waiting for a contact.

Legacy GPS receiver in Matlab

Investigation into using an SDR receiver to record RF signals of the L1 GPS band and calculate position solutions with the help of Navigation data downloaded from the Net. GPS signals are usually invisible when tuning to the L1 band (abou't 1.6GHz) and software is needed to make them visible. I was interested in seeing the signals so started writing some Matlab code. I got carried away and ended up calculating my geographic position.

50 Mbps UART in an FPGA: My intro into FPGA

I decided to try out FPGA. For my first foray I wondered if a 50Mb/s UART would be possible and if that would be a good first project. The learning curve for FPGA can be a bit tricky at times not made easier with languages that require pointless repetitive typing and IDEs that are both huge and clunky. However they are super interesting and I would highly recommend trying them out if for no other reason but to see something you most likely have never seen before.

SD card for the JPIC

A look into SD cards, a little under the hood and how to and to use them with the JPIC. I have updated the JADE environment for SD card support and now FAT32 file system can be used. So now you can record audio to and play audio from an attached SD card. I also experiment a bit with temperature/humidity and accelerometer modules.


The JPIC is my development board that came about as a continuation of my last post below (Fun with DSP). I was frustrated with other dev boards and their software (or lack thereof) such as Arduinos and ARMs. I wanted to have something I would enjoy programming on, so I made my own board and development environment for it. I wanted it super easy to use and something to both experiment with and learn with. I then wanted to give others the opportunity to use it as well, so, I made up some more and now have some that are for sale.

Fun with DSP

I start mucking around with DSP and in particular implementing various DSP functions onto a $6 dsPIC chip. however I get a little sidetracked and move on to neural networks. If you like big webpages you are going to love this page.


Experimening with digital SCA signals. SCA is a way to add another audio channel to an FM transmitter. DSCA (Digital SCA) is a digital version. Here I see how it goes


A program to demodulate and decode Classic Aero satellite communication ACARS. This program can be used with an RTL-SDR dongle and a homemade L band antenna to receive ACARS (Aircraft Communications Addressing and Reporting System) communication from satellites to Aeroplanes. Such information contains weather reports, flight plans etc.

GPS Basics

The Global Positioning System (GPS) is pretty cool. See how the signals can be used to figure out where you are in the world. Here we delve into the murky inner workings of GPS from the end users point of view. What are the signals that arrive at your Cell phone’s GPS receiver, and what does it do to turn these into an answer that tells you where you are. Find out that answers to these questions here.


A program to demodulate MSK signals. Its a coherent demodulator with performance similar to BPSK. It can be used with cheap $5 DDS modules as found on Ebay to create a long range transmitter while still producing side lobes low enough to be acceptable for transmission.

How this web site works

See how this Website is put together and how general HTML pages are incorporated.
I have updated the theme of my website after a long period of time of being unable to make any changes to it due to Microsoft pulling the rug from beneath my feet after they got rid of FrontPage.


The fascinating structure of a high speed modulation technique.

QAM idea

Eye diagram


An FM stereo encoder for FM stereo broadcasts. Implemented in software for a computer soundcard.

IIR pre-emphasis investigation and implementation

Interesting investigation into theory of IIR filters and how to design and implement a digital pre-emphasis filter.


How about computer plots and animations as art? art.

Cyclone Pam

Cyclone Pam taken using an RTL-SDR dongle as it approaches New Zealand

Jonti. Last modified Fri, 23 Jun 2023 19:50:58 GMT.